The Storms of Arctic Warming: Polar Amplification, Vortex Disruption to Set off Extreme Weather Events For US, UK Yet Again

It’s happening again.

A story that starts in the Arctic where abnormally warm temperatures for this time of year are in the process of disrupting the polar vortex, shoving its node out of the Arctic Ocean and pushing it all the way south over Hudson and Baffin Bay. The result is a core of extreme cold shoved much closer to related warmer, southerly regions. A highly unstable event that is likely to spawn extreme weather for the US and UK yet again.

This polar heat amplification and related extreme weather is a signature of human-caused global warming. And though it wears a grotesque mask of what some would call a normal Arctic oscillation, it is anything but.

The causes of this rapid Arctic amplification are manifold. First, human greenhouse gas emissions added more heat to the oceans and atmosphere. The polar sea ice, sitting atop a warming ocean went though a period of recession from the 1920s through the 1950s, hovered in about the same zone during the 60s and 70s and then commenced a more rapid melt phase from the 1980s onward.

This bleeding of oceanic heat has bent the Jet Stream ever northward over two zones — one over Svalbard and one over Alaska. And both these Jet Stream weaknesses allow warmer air to rush into the Arctic from the south. These various heat forcings cause the winter time polar vortex to wobble uneasily over a warming Arctic Ocean even as it is more frequently ripped apart by warm air incursions through the oceanic weak points. Meanwhile, these vortex disruption and collapse events spill cold air southward over the continents and into the Atlantic Ocean.

Yet one more Polar Vortex Disruption

And for this winter, such Arctic heat driven polar vortex disruption and collapse events have been the norm. This week is featuring yet one more — sparking extreme weather that will revisit both the US and UK over the coming days.

Today, the Arctic temperature anomaly was 2.68 degrees Celsius above the, already warmer than normal, 1979 to 2000 average. Areas near Svalbard, Alaska, and Baffin Bay showed extraordinary temperature departures in the range of 15 to 20 degrees Celsius above average. Meanwhile a zone of cold, Arctic air has been shoved southward over the US, setting up extreme temperature differentials over a relatively small area and putting in place conditions ripe for extreme weather.

A Tale of Three Storms

A large Pacific storm now in the process of leaping over the west coast blocking pattern is forecast to dump up to 5 inches of rain on a parched California before injecting itself into the highly unstable atmosphere over the central and eastern US. Areas in the center of the US such as Oklahoma may experience a range of weather from thunderstorms to tornadoes and precipitation running the gambit between snow, hail, ice, and rain. This system is predicted to spread out, covering a massive swath from Texas to Maine and incorporating at least two low pressure systems. It will draw in a deep flow of warmth and moisture from the Gulf of Mexico and this warm and moisture laden air will abruptly collide with the much colder Arctic air to the north. Extreme rain, ice and snowfall are certainly possible as this intense event is expected to last from Saturday through Monday.

Now a strong double barrel low pressure system is bringing gale force winds and heavy rains back to a United Kingdom that has suffered an almost constant assault of storms since the middle of December. Flood warnings have again been issued for multiple counties and regions just north of London, which experienced 60 degree temperatures earlier this week, are expected to see snow. The storm is expected to sweep through the UK on Friday and Saturday before exiting Sunday. A storm of similar intensity is then expected to return to the UK on Monday where the process of gales and floods are likely to again repeat.

(Sediment outflow from the swollen rivers of England and France on January 26 as yet another storm encroaches. Image source: Lance-Modis.)

In total, this worst continuous period of storms in UK history, has resulted in over a billion dollars in damages. Meanwhile, the storms are expected to continue through at least early March.

Overall, these extraordinary conditions cannot be entirely separated from the still-high temperature deviations occurring in the Arctic. Usually, by this time of year, the ice is solid enough and the warm air incursions are weak enough to allow at least some minor re-establishment of the polar vortex. Not so for 2014. The above average temperatures throughout the Arctic continue and show little sign of abatement as we head into March and the end of sea ice freeze season.

19 Comments

Yeah. The rains will come. But they’ll need multiple storms of this size to end it. GFS shows three. Euro shows only one. We’ll see if the blocking pattern re-establishes as the Euro indicates. California would do well to put its bets on the GFS ensemble.

Surely it’s not impossible that they’ll swing into exceptional flooding at some point – which will replenish the reservoirs I guess (but not necessarily the increasingly depleted underground aquifers) but potentially do it’s own additional damage (flood after drought tends to be worse than the reverse).

Hard to call it – one can’t discount that the whole region of the US is on the verge of going back to desert (and truly persistent drought). Mind you, I guess even in most deserts it rains sometimes…

The trend, long term, is more toward drought. But, as with Australia, the rain events that do come will be pretty extreme.

If the block shuts down, there’s a chance for them to get that extreme rain. But it diminishes over time. March is normally drier than most winter months, but with the Pacific Jet running the way it is, there could be a major late season delivery of severe storms.

With El Nino coming, the potential for extreme rain events rises pretty significantly into next winter.

Israel kind of got set up from the start, trying to establish a state on such a small piece of real estate in a desert with such poor water resources. The Jordan doesn’t even go anywhere, it just bottoms out in a salt reservoir. I pity the Palestinians who got this dumped on them, and much attention is paid to this conflict, but the general paucity of water in the region is going to drive ongoing warfare, I expect, and soon.

And as Robert noted the other day, what are people like the Saudis going to do when the oil runs out, or demand for some reason dries up?

Yep, you get those PDO/Nino values up and the west coast is pushed toward stronger rainfall during winter.

The block appears to be under assault due to the expected stream of moisture. GFS shows three storms on the way, Euro shows just one with the block re-establishing.

That hot pool in the North Pacific and the related abnormal warmth over Bering/Alaska/Beaufort wants to keep the block established. But the atmosphere is moving more toward positive PDO/El Nino.

Depending on the strength of El Nino, we could see extreme rainfall for California next winter. In any case, the rains that are on the way may help some. But with dry season ahead, they’d have to be pretty intense to avoid a rough summer.

james cole

I know I keep harping on this issue, but sometimes I just can’t help it. I have watched Britain get battered by these storms for so many months now that I have lost track. We all know the role of the melting arctic and jet stream disruptions in these storms. While floods and winds ravage the landscape, the government and parliament scheme to start fracking a large section of the country for fossil fuels. Can anyone see the irony in this? A human tragedy and folly of the highest order. And my near neighbor Canada is now a wholly owned petro-state. Tar Sands mining being it’s business plan going forward. Leaves me speechless!

Peter Sinclair at Climate Crock of the Week has interviews with Jennifer Francis and Kevin Trenberth on the role of the Arctic in the recent behavior of the jet stream. In the first video Sinclair provides a synopsis of Francis’ theory, in the second Trenberth’s criticism of it, then in the third Francis’ response to Trenberth’s criticism.

Phil

A very interesting article and very surprising that a someone senior in the BOM would come out so hard as it is a pretty conservative organisation although as a whole, is more involved in climate change issues – they contributed to the latest IPCC report. The comments to the article however are typical – see the ‘right wing fruit loops’ and ‘flat earthers’ providing comments about science – of course, they would not know science if it took on a physical form and appeared before them.

It will be interesting to see if the Western Australian government tries to reign the BOM in – the state and federal government after all is composed of climate change deniers and are sponsors of big mining including natural gas in Western Australia.